Abstract: An expansion joint for a modular flooring system in disclosed, which includes the slidable engagement of two subsections of the expansion joint. The expansion joint is sized such that it is equivalent in overall dimension to the intended adjacent modular floor tiles of which it will form a part within a matrix of such interlocked modular floor tiles. The expansion joint is provided with at least one slot on one module, corresponding to at least one locking pin on the other module. The slot receives and restrains the locking pin and permits the slidable engagement along the longitudinal axes thereof.